Thermionic method for quantitative determination of ammonia in concrete

FIELD: construction.

SUBSTANCE: method comprises the preliminary moistening of concrete sample and its subsequent heating, in which the thermal emission is carried out in case of discharging of 700 mm Hg and temperature of 80-300°C.

EFFECT: increase of the efficiency and acceleration of analysis.

1 dwg

 

The invention relates to the field of construction technologies and can be used for the quantitative determination of ammonia in concrete structures used in residential construction.

When using concrete slabs used additive type diamide acetic acid, potash (waste ammonia production), cement with fly ash, etc. Subsequently, in a residential area due to the hydrolysis of ammonia-containing compounds excreted ammonia, which creates uncomfortable conditions for housing. To select the method for reducing ammonia in the premises it is necessary to consider the ammonia content in the concrete.

The known method of determination of ammonia from a sealed temperature-controlled cameras placed in their samples at a temperature of 23±2°C and saturation, expressed as the ratio of the surface area of the sample to the volume of the chamber

While chemical studies of the air environment of the chambers is carried out using a gas chromatograph "Crystal 5000-2 (see Sanitary-hygienic evaluation of polymer and polymer-containing building materials and structures intended for use in the construction of residential, public and industrial buildings. HOWTO. MOO 2.1.2.1829-04, approved. Chief state sanitary doctor of the Russian Federation 06.01.2004).

The disadvantage�known method is the fact, the analysis was carried out for 5 days. In addition, at a temperature of 23±2°C the incomplete hydrolysis and thermal emission of ammonia ineffective. Defined in this way, the concentration of ammonia in mg/m of air does not allow to estimate the mass content of ammonia per ton of overlap that does not allow to choose the optimal technology for the reduction of ammonia in the volume of the room.

Known Kjeldahl method, which consists in heating the nitrogen-containing substance to the boil with enough concentrated sulfuric acid (G. Meir / Analysis and determination of structure of organic substances: the lane with it. / Under the editorship of Professor V. Rodionova and A. Kipriyanov. - 5th ed. - Kharkiv-Kyiv: State .nauch.-tech. publishing house of Ukraine, 1936. - Pp. 129-130).

The disadvantage of this method is the duration of boiling and subsequent distillation. With concentrated sulfuric acid at high temperature partially decomposed to SO3that leads to inaccurate determination of ammonia.

The technical problem solved by the claimed invention is to reduce the time for quantitative determination of ammonia in concrete due to the rapid and complete extraction of ammonia from concrete.

The problem is solved in that thermionic method for the quantitative determination of ammonia in concrete lies in the moist pre�completion of the concrete sample and its subsequent heating, where thermal emission is conducted in the vacuum of 700 mm Hg. CL. and a temperature of 80-300°C.

The essence of the claimed thermionic method for quantitative determination of ammonia in concrete is illustrated by a drawing, which schematically shows the installation of thermionic analysis.

Installation of thermionic analysis includes a chamber 1 made of PTFE and is made in the form of a cylinder with two screw caps. One of the covers of the chamber 1 is provided with two pipes, one of which is connected with made of glass sinks Richter 2. Absorbers Richter 2 filled with a solution of sulfuric acid at a concentration of 0.05 n and a volume of 5 cm3. Camera 1 is placed in an electric furnace with thermostat 3 4.

The claimed method is as follows.

For more rapid and complete excretion of ammonia sample of concrete must moisturize. The wetted sample of concrete is placed in the chamber 1 of the above-described installation of thermionic analysis. To extract the ammonia from the camera 1 connect the vacuum pump 3, which creates a vacuum of 700 mm Hg. V. to intensify the process of emission of ammonia from concrete. At a temperature of 150°C to heat enough 40 minutes at 200°C for 20 minutes. Under these conditions, there is rapid hydrolysis of ammonia-containing components of the concrete. After thermoemission from sinks Richter 2 is transferred to a conical flask and titrated with NaOH solution (caustic soda) concentration of 0.05 D. The amount of ammonia in the sample of concrete is calculated by the formula

With the mass of ammonia in the sample, ug/kg;

m - mass of sample, g;

1,225 - the amount of sulfuric acid in 5 ml of absorbing solution;

V - volume of NaOH used for the titration of a solution from the absorbers Richter, ml;

n1- number of sinks Richter;

n2is the correction factor determined by the formula

V1- the volume of NaOH solution (≈0,005 n), used for titration of 5 ml (0.005 n) sulfuric acid solution (blank solution), ml.

Thus, the claimed invention allows to reduce the time for quantitative determination of ammonia in concrete due to the rapid and complete extraction of ammonia from concrete.

Thermionic method for the quantitative determination of ammonia in concrete, which consists in the preliminary moistening of the concrete sample and its subsequent heating, in which thermal emission is conducted in the vacuum of 700 mm Hg. CL. and a temperature of 80-300°C.



 

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